Do panel moderators do that too?
So why is that? The event itself is just as important. You are asking the participants to invest their valuable time with you. Nowadays, there is a substantial probability that someone is taking a video and/or tweeting about the event – saving the good, bad, and the ugly for posterity.
Once you have done all the planning, take the time to legitimately practice the flow of the panel discussion. Some bits should be memorized (your introduction of the topic and the panelists as well as the closing). Others you need to vocalize (the sequence of questions) so you are completely comfortable with them and can easily shift them around. And when you “switch gears,” practice the transitions from one segment to another.
The point of all this practicing is so that you, as the panel moderator can be completely present to the conversation in the moment – making sure that the audience is getting great value from the conversation. And as a result, you’ll look brilliant!